A geographic information system (GIS) is an information system which combines and processes geographic data which occupies a geospatial position and various attribute data related to the geographic data and defined as a general organization of hardware, software, geographic data, and a human resource which is used to efficiently collect, store, update, manipulate, analyze, and output various types of geographic information.
Generally, a user interface is implemented as a GIS viewer in the geographic information system. The GIS viewer serves to visually show geographic data which is represented as a form of a map layer on a screen and an attribute value of each feature which forms the map layer to the user. The feature is a geographic data element having one of basic geometry types, such as a point, a line, or a polygon, which form one map layer.
Here, the geometry is a measurement and a feature of a geographic object called as a feature such as the point, the line, and the polygon and is used to represent a spatial element for the geographic feature in the GIS field.
One map layer is formed as one table in a data storing unit and one feature corresponds to one row in the table.
In order to view information corresponding to a specific feature in the GIS viewer, the feature is selected and attribute information which is connected to the selected feature is read out from a database and then provided through the screen. For example, if a border is represented based on an administrative district, each feature having a polygon shape which forms the map layer indicates one administrative district and includes various categorical data such as a name or a code of the administrative district and various numerical data such as a population, the number of buildings, and the number of households of the administrative district. If such various attribute information is present in the database, the feature is selected so that the attribute information may be directly checked on the GIS viewer. In this case, the attribute which may be checked by the user is limited to a type of an existing feature. For example, information on a part of a first administrative district or a region obtained by combining a part of second administrative district and third one is unknown because a feature of the region is not present in database.
Extraction of an overlaying region between two features is simply calculated using a function which is provided by a spatial database system. However, if calculation and analysis by a specific analysis model are required as mentioned in the above example, a separate external analysis tool needs to be used or a complex analysis model needs to be directly implemented in the user interface. If the model is modified, a source code of the viewer needs to be directly modified.